Field of Technology
The present disclosure relates to an organic light emitting display device, and more particularly, to an organic light emitting display device and a fabrication method thereof of an in-cell type touch integrated display device.
Description of the Related Art
A display device is used in electronic devices and the like. A touch screen has been implemented to allow a user to select a graphical object or region displayed on the screen.
The touch screen for a display device can be realized as an add-on type touch screen in which a touch panel is adhered on the display panel, or an in-cell type touch integrated display device in which touch electrodes and touch sensing lines are formed within the display panel. In particular, an in-cell type touch integrated display device is advantageous due to its improved touch sensitivity and thinness property.
A first substrate having a light emitting unit and a second substrate having a color filter, the in-cell type touch integrated display device includes touch electrodes configured with transmitting electrode (Tx) and receiving electrode (Rx) used in performing a touch operation on the second substrate, and to generate mutual capacitance within the touch electrodes, thereby measuring a change amount of the mutual capacitance generated at the time of touch to recognize whether or not there is a touch operation.
FIG. 1 is a view illustrating the cross-section of a display device having an in-cell structured touch panel in the related art.
Referring to FIG. 1, the display device 1 in the related art may include a lower substrate 10 formed to have a plurality of light emitting patterns for implementing an image and an upper substrate 30 bonded to the lower substrate 10 with a particular separation distance to implement protection from moisture permeation into the substrate, whereby the two substrates 10, 30 are bonded to each other using an adhesive 60.
The light emitting pattern layer 20 on the lower substrate 10 can include a light emitting unit for emitting light to an upper surface thereof and a driving unit for controlling the light emitting unit. Furthermore, the upper substrate 30 is formed to have a color filter layer 40 including a color filter for three primary colors (RGB: red, green, blue) to display color and a black matrix located at a side towards the lower substrate, and a touch electrode layer 50 including touch electrodes configured to recognize a user's touch contact operation and touch lines connected to the touch electrodes are formed on the color filter layer 40.
According to its structure, in the display device 1 of the related art, light corresponding to an image emitted from the light emitting pattern layer 20 is enters the color filter layer 40 provided on the upper substrate 30 to display a color image during a display operation, and also a touch operation is recognized according to a change of mutual capacitance on the touch electrode layer 50 when a touch sensing signal is generated by a user applying touch contact onto a surface of the upper substrate 30 during a touch operation.
Here, the viewing angle of light emitted to a front surface of the display device 1 through the upper substrate 30 during a display operation is determined by a distance between the upper substrate and the lower substrate.
FIGS. 2A and 2B are views illustrating a partial cross section of the display device in the related art, wherein the electrode 26 provided in a light emitting unit on the light pattern layer, and the color filter layer 40 and touch electrode layer 50 facing the electrode 26 are shown.
Here, the color filter layer 40 may include a color filter 41 for three primary colors and a black matrix 42 provided between portions of the color filters 41, and a planarization layer 44, and the touch electrode layer 50 may include a touch electrode 52 and a touch line 55.
Referring to FIGS. 2A and 2B, light (L1) passing through the electrode 26 of the lower substrate in a vertical direction can be viewed from the front surface of the display device, but light (L2) exiting at a particular angle (Θ) inclined from the vertical direction is blocked by the black matrix 42 due to its structure and thus not viewable. In other words, the viewing angle decreases as the separation distance between the upper substrate and the lower substrate increases.
In order to improve the foregoing problem, when configured with a decreased separation distance between the lower substrate and the upper substrate, a distance between the electrode 26 and the black matrix 42 decreases, and thus light (L2) is viewed even at the same angle (Θ). However, a distance between the electrode 26 and the touch electrode 52 also decreases (d1→d2) at the same time, and accordingly, a parasitic capacitance component formed between the electrode 26 and the touch electrode 52 increases (c1→c2). The parasitic capacitance component (c2) may have an effect on the touch electrode 52 to decrease the sensing characteristics, thereby reducing the overall sensitivity of the touch panel.
As a result, a distance (d1) above a predetermined level should be maintained between the electrode 26 and the touch electrode 52 on the lower substrate 10, resulting in a restriction in widening the viewing angle of the display device.